Antiphospholipid antibodies interfere with the body’s blood clotting process in a way that is not fully understood. Their presence increases a person’s risk of developing inappropriate blood clots (thrombi) in both arteries and veins. Antiphospholipid antibodies are most frequently seen in those with antiphospholipid syndrome (APS), an autoimmune disorder associated with blood clots (thrombotic episodes), a low platelet count (thrombocytopenia), or with pregnancy complications such as pre-eclampsia and recurrent miscarriages, especially in the 2nd and 3rd trimesters.

Is any test preparation needed to ensure the quality of the sample?

The Test

How is it used?

Beta-2 glycoprotein 1 antibody tests are used along with cardiolipin antibody and lupus anticoagulant testing to help diagnose the cause of an unexplained blood clot (thrombotic episode) or recurrent miscarriages, to help diagnose antiphospholipid syndrome (APS), or to detect the autoantibodies in someone with another autoimmune disorder. As beta-2 glycoprotein 1 antibody is less common than the other antiphospholipid antibodies, it may be ordered as a follow-up to those tests to provide the doctor with additional information. However, beta 2 glycoprotein 1 antibodies have been reported to be more specific than cardiolipin antibodies for the diagnosis of APS.

If all three of the initial antiphospholipid antibody tests for the IgG and IgM classes are negative, but APS is still suspected, then the IgA class of these antibodies may be tested, along with other less common antiphospholipid antibodies, such as anti-phosphatidylserine and anti-prothrombin. However, the value of testing for the IgA class of antiphospholipid antibodies remains controversial. According to the international consensus statement on APS, the presence of the IgA class (either anticardiolipin antibodies or beta-2 glycoprotein 1 antibodies) does not fulfill laboratory criteria for APS diagnosis.

If a beta-2 glycoprotein 1 antibody is detected, the same test will be repeated about 12 weeks later to determine whether its presence is persistent or temporary. If a person with an autoimmune disorder tests negative for antiphospholipid antibodies, testing may be repeated at a later time to determine if the person has begun to produce antibodies, as they may develop at any time in the course of disease.

When is it ordered?

Beta-2 glycoprotein 1 antibody tests and other antiphospholipid antibody testing may be ordered when a person has symptoms suggestive of a blood clot in a vein or artery, such as pain and swelling in the extremities, shortness of breath, and headaches. They also may be ordered when a woman has had recurrent miscarriages. These tests may be ordered initially, along with cardiolipin antibody and lupus anticoagulant testing, or as follow-up tests.

A beta-2 glycoprotein 1 IgA antibody test may sometimes be ordered when initial antiphospholipid antibody testing for the IgG and IgM class is negative but suspicion of APS is still strong.

When one of the antibody tests is positive, it will be repeated at least 12 weeks later to determine whether the antibody is temporary or persistent.

When a person with an autoimmune disorder tests negative for beta-2 glycoprotein 1 antibody, testing may be repeated periodically to screen for antibody development.

What does the test result mean?

Beta-2 glycoprotein 1 antibodies are most frequently seen with antiphospholipid syndrome (APS). Current diagnostic criteria for APS are based upon both clinical findings and the persistent presence of one or more antiphospholipid antibodies. If a high level of beta-2 glycoprotein 1 antibody is detected initially and then again 12 weeks later in a person with signs of APS, then it is likely that the person has the disorder. This is especially true if other antiphospholipid antibodies are also detected.

If a person is negative for beta-2 glycoprotein 1 antibodies but positive for other antiphospholipid antibodies and has signs and symptoms, then that person also likely has APS.

If a person is weakly to moderately positive for beta-2 glycoprotein 1 antibodies and weakly positive or negative for other antiphospholipid antibodies, then the antibody presence may be due to a condition other than APS. If subsequent testing is negative, then it is likely that the antibodies were temporary; this may be seen with an acute infection.

A single positive beta-2 glycoprotein 1 antibody result is not diagnostic of APS, and a negative result does not rule out antiphospholipid antibody development. They just indicate the presence or absence of the antibody at the time of testing.

2. Can beta-2 glycoprotein 1 antibody testing be performed in my doctor's office?

3. If I have antiphospholipid antibodies, will I definitely develop blood clots?

Not necessarily. They represent a risk factor but cannot predict whether an individual person will have recurrent blood clots. And, if a person does, the presence of the antibodies cannot predict the frequency or severity of clotting.

4. Should I tell a new doctor that I have antiphospholipid antibodies?

Yes, this is an important part of your medical history. Your doctor needs this information even if you don't have symptoms in order to tailor any procedures or medical treatment plans around this risk factor.

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Article Sources

NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

(Reviewed 2010 December 15). Learning About Antiphospholipid Syndrome (APS). National Human Genome Research Institute [On-line information]. Available online at http://www.genome.gov/17516396 through http://www.genome.gov. Accessed March 2011.

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This article was last reviewed on April 27, 2011. | This article was last modified on January 27, 2014.

The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.

The modified date indicates that one or more changes were made to the article. Such changes may or may not result from a full review of the article, so the two dates may not always agree.